TWI830871B - Method for producing alkaline earth metal carbonates - Google Patents

Abstract

The present invention provides a method for easily producing an alkaline earth metal carbonate whose particle growth is suppressed during heat treatment. The method can be suitably used for producing barium carbonate, which is a raw material for synthesizing barium titanate. The present invention relates to a method for producing alkaline earth metal carbonates, which includes the following steps: a mixing step, which is selected from hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides of alkaline earth metals. At least one alkaline earth metal compound in the group is mixed with carbon dioxide and/or a water-soluble carbonate compound; and a step of adding a water-soluble Group 4 transition metal compound, which is before and/or the above mixing step In the mixing step, a water-soluble Group 4 transition metal compound is added to an alkaline earth metal compound, at least one of carbon dioxide and/or a water-soluble carbonate compound, or a mixture thereof.

Description

Method for producing alkaline earth metal carbonates

The present invention relates to a method for producing alkaline earth metal carbonates.

In recent years, in order to make dielectric layers thinner and multilayered in multilayer ceramic capacitors (MLCCs) that are miniaturized and have larger capacities, it is important to oxidize barium titanate as a dielectric material and its raw material. The two raw materials, titanium and barium carbonate, are made into fine particles. In the above-mentioned calcination using the solid-phase synthesis method, it is known that barium carbonate undergoes particle growth during the temperature rise process. As a result, there was an abnormality in the particle size and other characteristics of the produced barium titanate powder. Therefore, in order to obtain uniform and fine barium titanate, it is necessary to suppress the growth of particles of barium carbonate due to heat. Previously, methods were being developed to suppress particle growth due to heat by subjecting barium carbonate to surface treatment using a titanium compound for neutralization (see Patent Documents 1 and 2). [Prior technical literature] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2013-28509 Patent Document 2: Japanese Patent Publication No. 2008-508170

[Problem to be solved by the invention]

As mentioned above, methods have been developed so far to suppress particle growth due to heat by subjecting barium carbonate to surface treatment using neutralization with a titanium compound. However, there are methods such as utilizing a neutralization reaction after the synthesis of barium carbonate. Surface treatment becomes a lengthy process. Furthermore, if conventional surface-treated barium carbonate is used to synthesize barium titanate, there is a risk that the formed surface treatment layer may be damaged due to shearing during the mixing with titanium oxide during synthesis.

In view of the above situation, an object of the present invention is to provide a method for easily producing an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment, and which can be suitably used for producing barium carbonate, a raw material for synthesizing barium titanate. [Technical means to solve the problem]

The present inventors conducted research on a method for easily producing an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment. As a result, they found that if an alkaline earth metal carbonate is produced using a production method including the following steps, the alkaline earth metal carbonate can be easily produced during heat treatment. The present invention has been completed by producing an alkaline earth metal carbonate whose particle growth is suppressed. That is, the production method includes a mixing step of mixing an inorganic acid salt selected from the group consisting of hydroxides, chlorides, and carbonates of alkaline earth metals. , mixing at least one alkaline earth metal compound from the group consisting of organic acid salts and oxides with carbon dioxide and/or a water-soluble carbonate compound; and adding a water-soluble Group 4 transition metal compound, which is Before and/or during the above mixing step, a water-soluble Group 4 transition metal compound is added to the alkaline earth metal compound and at least one of carbon dioxide and/or water-soluble carbonate compounds or a mixture thereof.

That is, the present invention is a method for producing alkaline earth metal carbonates, which is characterized by including the following steps: a mixing step of mixing alkaline earth metal hydroxides, chlorides, inorganic acid salts other than carbonates, and organic acids. Mixing at least one alkaline earth metal compound from the group consisting of salts and oxides with carbon dioxide and/or a water-soluble carbonate compound; and a step of adding a water-soluble Group 4 transition metal compound, which is part of the mixing step Before and/or in the mixing step, a water-soluble Group 4 transition metal compound is added to the alkaline earth metal compound and at least one of carbon dioxide and/or water-soluble carbonate compounds or a mixture thereof.

The alkaline earth metal compound is preferably a barium compound or a strontium compound.

The above-mentioned water-soluble Group 4 transition metal compound is preferably a water-soluble titanium compound.

The above-mentioned manufacturing method preferably further includes the step of adding citric acid and/or its salt before the mixing step and/or during the mixing step, to at least one of the alkaline earth metal compound and carbon dioxide and/or the water-soluble carbonate compound. or a mixture thereof, add citric acid and/or its salt.

Furthermore, the present invention is also a method for producing barium titanate, which is characterized by including the following steps: a step of obtaining barium carbonate, a mixing step of mixing the barium carbonate and a titanium compound, and a mixture obtained in the mixing step. Carry out the step of calcination; the above-mentioned step of obtaining barium carbonate is achieved by the following steps: a mixing step, which is selected from barium hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, oxides At least one barium compound in the group is mixed with carbon dioxide and/or a water-soluble carbonate compound; and a step of adding a water-soluble Group 4 transition metal compound is preceded and/or mixed with the mixing step In the step, a water-soluble Group 4 transition metal compound is added to the barium compound, at least one of carbon dioxide and/or water-soluble carbonate compounds, or a mixture thereof. [Effects of the invention]

Since the method for producing an alkaline earth metal carbonate of the present invention can easily produce an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment, it can be suitably used to produce electronic components such as ceramic capacitors that are components of electronic equipment. Materials, air electrode materials of solid oxide fuel cells, oxide superconductor materials, and other fine particle synthesis raw materials, namely barium carbonate, etc., are particularly suitable for use in a method of manufacturing barium carbonate used as a raw material for synthesizing electronic materials.

Hereinafter, preferred embodiments of the present invention will be specifically described. However, the present invention is not limited to the following description, and may be appropriately modified and applied within the scope that does not change the gist of the present invention.

1. Manufacturing method of alkaline earth metal carbonate The method for producing alkaline earth metal carbonates of the present invention is characterized by including the following steps: a mixing step, which is selected from hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides of alkaline earth metals. Mixing at least one alkaline earth metal compound in the group with carbon dioxide and/or a water-soluble carbonate compound (hereinafter, also referred to as the mixing step); and the step of adding a water-soluble Group 4 transition metal compound, which are Before and/or during the mixing step, a water-soluble Group 4 transition metal compound is added to the alkaline earth metal compound and at least one of carbon dioxide and/or water-soluble carbonate compounds or a mixture thereof. In this way, at least one alkaline earth metal compound selected from the group consisting of hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides of alkaline earth metals, and carbon dioxide and/or water-soluble At least one of the carbonate compounds or a mixture thereof, and a water-soluble Group 4 transition metal compound is added before and/or during the mixing, whereby an alkaline earth metal carbonic acid whose particle growth is suppressed during heat treatment can be obtained. Salt, the reason is considered to be as follows. The particle growth of alkaline earth metal carbonate during heat treatment is caused by the contact between alkaline earth metal carbonate particles during heat treatment. In this regard, it is considered that when the production method of the present invention is used, the presence of the Group 4 transition metal compound causes alkaline earth metal carbonate particles to be generated when the alkaline earth metal carbonate is heat treated, which is the cause of particle growth. Before contacting each other, the Group 4 transition metal compound and the particles of the alkaline earth metal carbonate are brought into contact, thereby hindering the growth of the particles of the alkaline earth metal carbonate. In the method for producing an alkaline earth metal carbonate of the present invention, in the step of producing an alkaline earth metal carbonate from a raw material, a heat treatment of the alkaline earth metal carbonate is simultaneously performed to suppress particle growth. Therefore, after the alkaline earth metal carbonate is synthesized, Compared with the conventional method of surface treatment using a neutralization reaction or the like, an alkaline earth metal carbonate whose particle growth is suppressed during heat treatment can be easily obtained, which is advantageous in this regard. The alkaline earth metal carbonate obtained by the manufacturing method of the present invention can also be called an alkaline earth metal carbonate containing a Group 4 transition metal element. The manufacturing method of the present invention can also be called an alkaline earth metal carbonate containing a Group 4 transition metal element. Method for manufacturing metal carbonates.

The above-mentioned alkaline earth metal compound only needs to be at least one selected from the group consisting of hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides of alkaline earth metals, and is preferably selected from the group consisting of At least one of the group consisting of hydroxides and oxides. In terms of higher solubility in water and higher reaction efficiency in the reaction into carbonate, hydroxide is more preferred. Examples of inorganic acid salts and organic acid salts other than carbonates include chlorates, acetates, nitrates, and the like.

The alkaline earth metal compound is preferably a barium compound or a strontium compound. As mentioned above, barium carbonate is used as a "raw material for the production of barium titanate by a solid-phase synthesis method", and strontium carbonate is similarly used as a "raw material for the production of strontium titanate". Therefore, as one of the preferred embodiments of the present invention, the method for producing alkaline earth metal carbonate of the present invention is used as a method for producing barium carbonate or strontium carbonate.

Examples of the water-soluble carbonate compound include alkali metal or ammonium carbonates, bicarbonates, hydroxide carbonates, and the like. Examples of water-soluble carbonates include ammonium carbonate, sodium carbonate, potassium carbonate, and the like, and one or more of these may be used. Examples of water-soluble hydrogen carbonate include sodium hydrogen carbonate, potassium hydrogen carbonate, and the like. Examples of the water-soluble hydroxide carbonate include sodium carbonate hydroxide, potassium carbonate hydroxide, and the like. In addition, in the present invention, "water-soluble" means dissolving 5 g or more per 100 g of water.

In the above-mentioned mixing step, it is preferable to use the number of moles of carbon dioxide or the water-soluble carbonate compound (in the case of using both, the total moles) relative to 1 mole of the alkaline earth metal atom contained in the alkaline earth metal compound. The number of ears) becomes 0.7 mol or more, and then mix. More preferably, it is mixed so that it may become 0.8 mol or more. From an economic point of view, it is preferable to mix so that the alkaline earth metal atom contained in the alkaline earth metal compound becomes 3 moles or less per 1 mole of the alkaline earth metal atoms. Among them, when carbon dioxide is used, it is more preferable to mix it so that the number of moles of carbon dioxide becomes 1 mole or more per 1 mole of alkaline earth metal atoms contained in the alkaline earth metal compound. Thereby, the yield of the alkaline earth metal carbonate obtained can be improved. It is particularly preferable to mix it so that it becomes 1.6 mol or more. In addition, when using a water-soluble carbonate compound, from the economical point of view, it is more preferable that the mole number of the water-soluble carbonate compound is 1 mole of the alkaline earth metal atom contained in the alkaline earth metal compound. Mix so that it becomes 1.5 mol or less.

The above-mentioned water-soluble Group 4 transition metal compound only needs to be a compound of a Group 4 transition metal. Preferably, it is a compound of any one of titanium, zirconium, and hafnium. From an economical aspect, a compound of titanium is more preferable. . In addition, the Group 4 transition metal compound only needs to be a water-soluble compound, and halides such as fluoride, chloride, bromide, and iodide, or lactates, ammonium lactate salts, sulfates, and peroxyacid salts can be used. One or more types of alkoxides, etc. Among these, halides, lactates, and ammonium lactates are preferred. More preferably, it is a chloride, so it is possible to obtain an alkaline earth metal carbonate in which particle growth during heat treatment is more fully suppressed.

Regarding the addition amount of the above-mentioned water-soluble Group 4 transition metal compound, if the effect of suppressing the particle growth of the produced alkaline earth metal carbonate during heat treatment is fully exerted and the production cost are taken into consideration, relative to the alkaline earth to be used as the raw material The value of the metal compound converted into 100 parts by weight of alkaline earth metal carbonate is preferably 0.5 to 10 parts by weight based on Group 4 transition metal elements. More preferably, it is 1 to 7 parts by weight, and even more preferably, it is 2 to 5 parts by weight.

The method for producing the alkaline earth metal carbonate of the present invention preferably further includes the step of adding citric acid and/or its salt, which is added to the alkaline earth metal compound, carbon dioxide and/or before the above mixing step and/or during the mixing step. Citric acid and/or its salt is added to at least one of the water-soluble carbonate compounds or a mixture thereof. By adding citric acid and/or its salt, the particle growth of the obtained alkaline earth metal carbonate during heat treatment can be more fully suppressed.

Examples of the salt of citric acid include salts of Group 1 elements of the periodic table such as lithium, sodium, and potassium, or salts of Group 2 elements of the periodic table such as magnesium, calcium, and strontium, and one or more of these may be used. .

Regarding the addition amount of the above-mentioned citric acid and/or its salt, when taking into account the effect of fully suppressing the particle growth of the produced alkaline earth metal carbonate during heat treatment and the production cost, relative to the amount of alkaline earth contained in the alkaline earth metal compound 100 moles of metal atoms, preferably 0.1 to 10 moles. More preferably, it is 0.5-5 mol, and still more preferably, it is 1-3 mol.

The method for producing an alkaline earth metal carbonate of the present invention may further include the following steps: before and/or during the mixing step, adding at least one of an alkaline earth metal compound, carbon dioxide, and/or a water-soluble carbonate compound, or both. To the mixture of polycarboxylic acids and/or salts thereof, at least one of polycarboxylic acids other than citric acid and/or salts thereof, anhydrides thereof, or salts thereof (hereinafter referred to as polycarboxylic acids, etc.) is added. By using citric acid and/or its salts, polycarboxylic acids, etc. in combination, finer alkaline earth metal carbonates can be produced.

As the above-mentioned polycarboxylic acid, any one of tartaric acid, succinic acid, malic acid, maleic acid, malonic acid, and 1,2,4-benzenetricarboxylic acid is preferred. Among these, any one of tartaric acid, 1,2,4-benzenetricarboxylic acid, malic acid, and maleic acid is more preferred, and tartaric acid or 1,2,4-benzenetricarboxylic acid is even more preferred.

The addition amount of the above-mentioned polycarboxylic acid and the like is preferably 1.10 to 9.90 mol% based on 100 mol% of alkaline earth metal atoms in the alkaline earth metal compound. More preferably, it is 1.25-8.00 mol%, and still more preferably, it is 2.00-6.5 mol%.

In the production method of alkaline earth metal carbonate of the present invention, the water-soluble Group 4 transition metal compound may be added to any one of the alkaline earth metal compound, carbon dioxide and/or the water-soluble carbonate compound, or may be added to both. It can be added to the mixture after mixing, and the period of addition can be the above-mentioned mixing step, or before it, or both of them. When carbon dioxide is used, it is preferable to add water-soluble At least a portion of the Group 4 transition metal compound is added to the alkaline earth metal compound before mixing with carbon dioxide. By sufficiently mixing at least a part of the Group 4 transition metal compound with an alkaline earth metal compound in advance and then mixing it with carbon dioxide, the Group 4 transition metal compound can be uniformly and highly dispersed in the obtained alkaline earth metal carbonate. Metal compounds can more fully exert the effect of inhibiting particle growth during heat treatment. The amount of the Group 4 transition metal compound mixed with the alkaline earth metal compound in advance is preferably 0.5% by weight or more of the total Group 4 transition metal compound added. More preferably, it is 1.0 weight% or more.

In the production method of alkaline earth metal carbonate of the present invention, the addition period when adding citric acid and/or its salt is also the same as the addition of the above-mentioned water-soluble Group 4 transition metal compound. When carbon dioxide is used, , it is preferable to add at least a part of citric acid and/or its salt to the alkaline earth metal compound before mixing with carbon dioxide. The amount of citric acid and/or its salt mixed with the alkaline earth metal compound in advance is preferably 0.1% by weight or more of the total added citric acid and/or its salt. More preferably, it is 1.0 weight% or more.

In the above mixing step, when the alkaline earth metal compound and carbon dioxide are mixed, the alkaline earth metal compound only needs to be brought into contact with carbon dioxide. It is preferred to add a solvent to the alkaline earth metal compound to prepare a raw material solution, and then mix the raw material solution with carbon dioxide. Mix. In this case, the solvent is not particularly limited as long as it is an aqueous medium. Water, a mixture of water and a water-soluble organic solvent (methanol, ethanol, acetone, etc.) can be used, and water is preferred. That is, as one of the preferred embodiments of the present invention, an aqueous solution of an alkaline earth metal compound and carbon dioxide are mixed and reacted. The concentration of the alkaline earth metal compound in the raw material solution is not particularly limited, but it is preferably 0.03 to 1.58 mol/L in terms of alkaline earth metal ions, more preferably 0.16 to 1.27 mol/L, and still more preferably 0.16 to 0.32 mol/L.

When the aqueous alkaline earth metal compound solution and carbon dioxide are mixed and reacted, the mixing method is not particularly limited as long as they are allowed to react. The aqueous alkaline earth metal compound solution and carbon dioxide can be sucked into a pump, mixed, and mixed. methods of such reactions. In this method, the alkaline earth metal compound aqueous solution and carbon dioxide are sufficiently stirred in the pump, so that the reaction can be fully carried out. In addition, by connecting a plurality of pumps in series and performing the reaction in multiple stages, the reaction can be carried out more fully, and a large amount of alkaline earth metal carbonate can be produced efficiently, so it is also suitable for industrial production. In this way, as one of the preferred embodiments of the present invention, the following pump reaction is performed. In the present invention, hydroxides, chlorides, inorganic acid salts other than carbonates, and organic acid salts of alkaline earth metals are selected. A mixing step in which at least one alkaline earth metal compound in a group of oxides is mixed with carbon dioxide; the above-mentioned pump reaction involves sucking an aqueous solution of an alkaline earth metal compound and carbon dioxide into a pump, mixing them in the pump, and causing the reactions.

In the above mixing step, when a water-soluble carbonate compound is used, it suffices to bring the alkaline earth metal compound into contact with the water-soluble carbonate compound. It is preferable to contact either the alkaline earth metal compound, the water-soluble carbonate compound, or the water-soluble carbonate compound. A solvent is added to the two to prepare a raw material solution and then mixed. As a solvent in this case, the same thing as mentioned above is preferable. When a solvent is added to the alkaline earth metal compound to prepare a raw material solution, the concentration of the alkaline earth metal compound in the raw material solution is preferably the same as above. When a solvent is added to a water-soluble carbonate compound to prepare a raw material solution, the concentration of the water-soluble carbonate compound in the raw material solution is not particularly limited, but is preferably 0.02 to 1.90 mol/L based on carbonate ions, and more preferably 0.02 to 1.90 mol/L in terms of carbonate ions. Preferably, it is 0.11-0.48 mol/L, More preferably, it is 0.11-0.35 mol/L.

In the above mixing step, in order to obtain fine alkaline earth metal carbonate particles, it is preferable to mix the aqueous alkaline earth metal compound solution with carbon dioxide and/or the water-soluble carbonate compound in a manner such that the pH of the mixed liquid obtained is 12 or less. , the alkaline earth metal compound aqueous solution and carbon dioxide and/or water-soluble carbonate compounds are mixed and reacted. It is more preferable to mix so that the pH of a mixed liquid may become 8 or less, and it is still more preferable to mix so that the pH may become 7 or less. In addition, the pH of the mixed liquid is usually 5 or more.

The temperature at which the above-mentioned mixing step is performed is not particularly limited, but is preferably 10 to 70°C, for example. By carrying out the reaction at such a temperature, the reaction between the alkaline earth metal compound and carbon dioxide and/or the water-soluble carbonate compound can proceed sufficiently. The temperature is more preferably 15 to 50°C, and still more preferably 20 to 40°C.

The method for producing alkaline earth metal carbonate of the present invention may also include other steps besides the above-mentioned steps. Examples of other steps include a purification step, a drying step, and a pulverizing step of the produced alkaline earth metal carbonate. The purification step of alkaline earth metal carbonate can be carried out by filtration, water washing, etc. The drying temperature of the alkaline earth metal carbonate in the drying step is preferably 60 to 200°C. More preferably, it is 80~130℃.

2. Manufacturing method of barium titanate As described above, the method for producing alkaline earth metal carbonate of the present invention is a method for producing barium carbonate in which particle growth during heat treatment is sufficiently suppressed. In this way, barium carbonate can be suitably used as a raw material for producing barium titanate. Furthermore, one aspect of the present invention is also a method for producing barium titanate, which includes the step of producing barium carbonate using the method of producing alkaline earth metal carbonate of the present invention, that is, the method includes the following steps: obtaining barium carbonate, The mixing step of mixing the barium carbonate and the titanium compound, and the step of calcining the mixture obtained in the mixing step; the above-mentioned step of obtaining barium carbonate is achieved by the following steps: the mixing step, which is selected from barium At least one barium compound from the group consisting of hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides is mixed with carbon dioxide and/or water-soluble carbonate compounds; with the addition of water-soluble The step of adding a water-soluble Group 4 transition metal compound to at least one of the barium compound and carbon dioxide and/or the water-soluble carbonate compound before and/or during the mixing step. Transition metal compounds.

Examples of the titanium compound used in the mixing step of mixing the barium carbonate and the titanium compound include titanium oxide, metatitanic acid, orthotitanic acid, titanium hydroxide, etc., and one or more of these can be used. .

Regarding the amount of the titanium compound used in the mixing step of mixing barium carbonate and the titanium compound, taking into account the yield and manufacturing cost of barium titanate, it is calculated based on 100 moles of barium atoms contained in the barium carbonate. , the amount of titanium atoms contained in the titanium compound is preferably 100.1 to 101 moles. More preferably, the amount is 100.3 to 100.6 moles.

In the step of calcining the mixture obtained in the above mixing step of mixing barium carbonate and titanium compound, the calcining temperature is preferably 900 to 1450°C. More preferably, it is 1000~1350℃.

The manufacturing method of barium titanate of the present invention may also include other steps besides the above-mentioned steps. Examples of other steps include a purification step, a drying step, and a pulverizing step of the produced barium titanate. Example

In order to explain the present invention in detail, specific examples are given below, but the present invention is not limited to these examples. Unless otherwise stated, "%" and "wt%" mean "% by weight (% by mass)". In addition, the measurement methods of each physical property are as follows.

(Example 1) After dissolving 145 g of barium hydroxide octahydrate in pure water, 2.3 moles of a citric acid monohydrate aqueous solution (Wako Pure Chemical) was added to 100 moles of barium ions in the barium hydroxide. Industries Co., Ltd.), and an aqueous solution of titanium tetrachloride (manufactured by OSAKA Titanium Technologies Co., _Ltd. , 150 g/ L). Next, dilute with pure water so that the final concentration becomes 72.5 g/L as barium hydroxide octahydrate (0.23 mol/L as barium ions) to prepare a barium hydroxide-citric acid aqueous solution (raw material A ). The liquid temperature at this time was adjusted to 32°C. In the reaction device shown in Figure 1, raw material A is put into the suction port of pump P1 at a flow rate of 400 ml/min. At the same time, carbon dioxide was blown at 4.2 L/min into the flow path of the raw material A toward the pump P1 so that the pH would be 6.0 to 7.0, and the reaction was performed. The reaction device used was a magnetic pump P1, P2 (manufactured by IWAKI Co., Ltd., MD-10K-N) and P3 (manufactured by IWAKI Co., Ltd., MD-15R-N) connected to three stages as shown in Figure 1 . The distillate at the initial stage of the reaction was discarded for 1 minute, and the reaction slurry was recovered. The slurry was immediately filtered and washed with water, and the water-containing filter cake was dried at 100°C. After drying, the dried material is pulverized using a pulverizer to obtain powdered barium carbonate.

(Example 2) Except having changed titanium tetrachloride in Example 1 into titanium lactate (ORGATIX TC-315 manufactured by Matsumoto Fine Chemical Co., Ltd.), the same procedure as in Example 1 was performed to obtain barium carbonate.

(Example 3) Except having changed titanium tetrachloride in Example 1 into ammonium titanium lactate (ORGATIX TC-335 manufactured by Matsumoto Fine Chemical Co., Ltd.), the same procedure as in Example 1 was performed to obtain barium carbonate.

(Example 4) The operation was carried out in the same manner as in Example 1, except that the amount of titanium tetrachloride added in Example 1 was changed to 0.5 parts by weight as Ti relative to 100 parts by weight of barium hydroxide converted into barium carbonate. Barium carbonate is produced.

(Example 5) The operation was carried out in the same manner as in Example 1, except that the amount of titanium tetrachloride added in Example 1 was changed to 1.0 parts by weight as Ti relative to 100 parts by weight of barium hydroxide converted into barium carbonate. Barium carbonate is produced.

(Example 6) The operation was performed in the same manner as in Example 1, except that the addition amount of titanium tetrachloride in Example 1 was changed to 5.0 parts by weight as Ti relative to 100 parts by weight of barium hydroxide converted into barium carbonate. Barium carbonate is produced.

(Example 7) Except having changed the barium hydroxide octahydrate in Example 1 into strontium hydroxide octahydrate, the same procedure as in Example 1 was performed to prepare strontium carbonate.

(Comparative example 1) Except for not adding titanium tetrachloride in Example 1, the same procedure as in Example 1 was performed to obtain barium carbonate.

(Comparative example 2) Strontium carbonate was produced in the same manner as in Comparative Example 1, except that the barium hydroxide octahydrate in Comparative Example 1 was changed to strontium hydroxide octahydrate.

[evaluation] The barium carbonate or strontium carbonate obtained in Examples 1 to 7 and Comparative Examples 1 and 2 was evaluated as follows. ＜Evaluation of heat resistance＞ Put 1 g of barium carbonate or strontium carbonate sample into a magnetic crucible, and heat it to 600°C at a heating rate of 200°C/hour under the atmosphere and keep it for 30 minutes. Thereafter, it was allowed to cool back to room temperature to obtain a heat-treated sample. The BET specific surface area of the sample before and after heat treatment was measured using a specific surface area measuring device Macsorb manufactured by Mountech. The results are shown in Table 1. ＜Analysis of titanium concentration＞ For barium carbonate or strontium carbonate, elemental analysis is performed by using the element-containing scanning function of a fluorescence X-ray analyzer (manufactured by RIGAKU Co., Ltd., model ZSX PrimusII), that is, EZ scanning. Specifically, by setting the pressed sample on the measurement sample stage and selecting the following conditions (measurement range: F-U, measurement diameter: 30 mm, sample form: oxide, measurement time: longer, atmosphere: vacuum), respectively The Ba or Sr content and the Ti content are measured, and the weight part of Ti relative to 100 parts by weight of barium carbonate or strontium carbonate is calculated using the following formula. The results are shown in Table 1. Parts by weight of Ti relative to 100 parts by weight of barium carbonate or strontium carbonate = {Ti content [g]/[(Ba or Sr content [g]/Ba or Sr atomic weight [g/mol]) × barium carbonate or strontium carbonate molecular weight [g/mol]]} × 100 ＜Appearance evaluation＞ Using a scanning electron microscope (SEM) (product name "JSM-6510A", manufactured by Japan Electronics Co., Ltd.), the barium carbonate or strontium carbonate sample that was subjected to the same heat treatment as the above heat resistance evaluation was examined before and after heat treatment. Samples are observed. The results are shown in Figures 2 to 8. The SEM photos in Figures 2 to 8 are at a magnification of 30,000 times.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2 alkaline earth metal compounds Barium hydroxide Barium hydroxide Barium hydroxide Barium hydroxide Barium hydroxide Barium hydroxide Strontium hydroxide Barium hydroxide Strontium hydroxide Citric acid (mol%) 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Group IV transition metal compounds Element Titanium tetrachloride Titanium lactate Ammonium titanium lactate Titanium tetrachloride Titanium tetrachloride Titanium tetrachloride Titanium tetrachloride - - Adding amount (※1) 2.0 2.0 2.0 0.5 1.0 5.0 2.0 - - XRF analysis (※2) 3.0 3.0 2.7 0.6 1.3 12.6 2.4 Not detected Not detected BET value (m ² /g) Before heat treatment 24.8 27.1 25.9 26.7 24.9 48.2 35.9 27.7 23.1 After heat treatment at 600℃ 12.6 10.6 10.3 10.7 11.9 14.5 16.9 6.0 12.4 (※1) Parts by weight of Ti relative to 100 parts by weight of the alkaline earth metal hydroxide of the raw material converted into carbonates (※2) Contained in the alkaline earth metal carbonate before heat treatment relative to the alkaline earth metal carbonate 100 parts by weight of Ti

As shown in Table 1, the barium carbonate or strontium carbonate of Examples 1 to 7 prepared by adding a titanium compound was compared with the barium carbonate or strontium carbonate of Comparative Examples 1 and 2 without adding a titanium compound. The change ratio of the previous BET specific surface area becomes smaller. Moreover, when observing Figures 2 to 8, it is confirmed that in Figure 8, compared with Figures 2 to 7, the barium carbonate particles after heat treatment become larger. From these contents, it was confirmed that particle growth during heat treatment is suppressed by adding a titanium compound when producing an alkaline earth metal carbonate. Furthermore, based on the comparison of Examples 1 to 7, it was confirmed that by setting the addition ratio of the titanium compound to a specific range, particle growth during heat treatment can be more effectively suppressed.

P1,P2,P3: pump

[Fig. 1] is a conceptual diagram showing an apparatus for producing barium carbonate in the Example. [Fig. 2] These are electron micrographs of the barium carbonate produced in Example 1 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 3] These are electron micrographs of the barium carbonate produced in Example 2 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 4] These are electron micrographs of the barium carbonate produced in Example 3 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 5] These are electron micrographs of the barium carbonate produced in Example 4 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 6] These are electron micrographs of the barium carbonate produced in Example 5 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 7] These are electron micrographs of the barium carbonate produced in Example 6 before heat treatment and after heat treatment at 600°C×30 minutes. [Fig. 8] It is an electron microscope photograph of the barium carbonate produced in Comparative Example 1 before heat treatment and after heat treatment at 600°C×30 minutes.

Claims (4)

A method for manufacturing alkaline earth metal carbonates, which includes the following steps: a mixing step, which is selected from the group consisting of hydroxides, chlorides, inorganic acid salts, organic acid salts, and oxides of alkaline earth metals other than carbonates. At least one alkaline earth metal compound in the group is mixed with carbon dioxide and/or a water-soluble carbonate compound; and the step of adding a water-soluble Group 4 transition metal compound and citric acid and/or its salt is based on the mixing Before the step and/or during the mixing step, a water-soluble Group 4 transition metal compound and citric acid and/or a mixture of the alkaline earth metal compound and at least one of carbon dioxide and/or water-soluble carbonate compounds are added. Or its salt. The method for producing an alkaline earth metal carbonate according to claim 1, wherein the alkaline earth metal compound is a barium compound or a strontium compound. The method for producing an alkaline earth metal carbonate according to claim 1 or 2, wherein the water-soluble Group 4 transition metal compound is a water-soluble titanium compound. A method for manufacturing barium titanate, which is characterized in that it includes: a step of obtaining barium carbonate, a mixing step of mixing the barium carbonate and a titanium compound, and a step of calcining the mixture obtained in the mixing step; the above-mentioned step of obtaining carbonic acid The step of barium is achieved by the following steps: a mixing step, which is at least one selected from the group consisting of barium hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides. a barium compound, mixed with carbon dioxide and/or a water-soluble carbonate compound; and a step of adding a water-soluble Group 4 transition metal compound and citric acid and/or its salt, which is before and/or mixed with the mixing step In the step, a water-soluble Group 4 transition metal compound and citric acid and/or a salt thereof are added to the barium compound, at least one of carbon dioxide and/or a water-soluble carbonate compound, or a mixture thereof.

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